Yamaha Yz465h
YAMAHA YZ465H
CYCLE WORLD TEST
The Hole-Shot King Gets Better
Yamaha's 1980 YZ465G set new standards for horsepower and brakes. But best of all, the rest of the package, things like controls, wheels, and frame, let the 465 racer take full advantage of the power and brakes. A strong running 450 Maico was about the only bike capable of giving competition to the 465. We couldn't find much wrong with our test bike last yeat but figured the 1981 YZ465H would be even better. And it is.
Many small items have been improved r honed to perfection. But the most ob vious improvement is the forks. They're KYB leading axle units with 43mm stan hion tubes. Travel remains the same, 11.8 in., but almost everything else about them is different. The lower castings are natu rally larger to accommodate the larger stanchions and internal bushings ensure smooth action. Damping rods, springs and triple clamps are new items. The clamps are aluminum and sport double pinch bolts, and the top one is equipped with rubber handlebar pedestals. The rubber compound and design are new so the bars don’t feel as loose as before. Air caps are provided but like last year, Yamaha recommends no air pressure. The stanchions can still be moved up and down for steering quickness but not as much as before due to shorter tubes—an effort to keep weight down.
Rear suspension is also better. Rebound damping adjustments have increased from 18 to 24 and compression damping has been reduced by 10 percent. The aluminum shock body is unchanged but the reservoir is larger and anodized gold. Damping adjustment is a simple reach under the rear fendef and turn; spring preload is accomplished at the same location but requires slightly more time to do and the use of a large wrench, supplied with each bike.
Externally the 465 engine looks the same; internally the porting is slightly different. The ignition has more spark at lower revs to make starting easier, the carburetor has more precise jetting and the pipe is new. The bulged headpipe Yamaha raved about last year is replaced with one that’s shaped normally. Additionally, the cones are different. The silencer is the same effective, non-rebuildable unit. Bore and stroke remain unchanged at 85 and 82mm. The cylinder is aluminum with a steel bore so rebores are possible. In fact Yamaha lists four oversize pistons for the 465. A six-petal stainless steel reed valve is placed between the carburetor and intake port. Past experience has proven it effective and long lived; the petals usually last for a complete season before needing replacement.
Some racers experienced transmission troubles with the early YZ465s, mainly low gear. The gear was strengthened later in the model year and the ’81 has the stronger gear. The other gears are treated to extra hardening. The large multiplate clutch and helical primary drive are unchanged. But the clutch actuating cam has been redesigned for an easier pull at the dog-legged lever, and the clutch cable guide by the shock reservoir is new. It longer pinches the excellent cable. Another small change is the transmission vent. The vent goes through the clutch actuating mechanism, reducing oil blowing during hard use.
Hubs and wheels look the same; the front is, the rear isn’t. The rear hub is slightly wider than before and the sprocket bolt pattern is slightly changed. The sprocket also attaches differently. Studs have been used for several years; the new unit has bolts with tapered heads. Lightening holes are no longer used around the sprocket attachment area and the spoke flange on the brake side is thicker. Rims are still D.I.D. aluminum, anodized a gold color for ’81. The rear brake is still full-floating with a parallel static arm, but the front pivot is better protected with a rubber boot.
Last year’s double leading shoe front brake is retained. It will stop the bike quicker than many are prepared for. Our ’80 was a little touchy but the ’81 doesn’t seem as sensitive. Maybe we are better prepared for the results of pulling the front brake after riding an ’80 for a year.
Most controls on the H are new. The shift lever folds and it’s slightly longer than last year’s, hand levers are doglegged and slightly shorter than before, the throttle is a new gear driven straightpull unit with a clear top, and the grips are a different design. About the only parts unchanged are the kick lever and rear brake pedal. They were some of the best around anyway. The aluminum brake pedal has a steel claw top so muddy boots don’t slip and the claw is easily sharpened with a file when dull. The forged steel kick lever has a ribbed boot contact surface. It folds out of the way when not in use and doesn't hurt the kicker's foot when used. Last year's chrome-moly steel frame is little changed. The only change is the steering head angle; it's steeper, 28.Y compared to 29.5 before.
Footpegs are new and support the boot sole over a wider surface. They are about a half inch higher than before. They still hold mud but don't stick up when fully covered with goo.
The neat aluminum swing arm fron last year is unchanged except for theaxic slots. They are wider to accommodate thc 3mm Iaraer rear axle.
All single shock motocrossers have a problem trying to fit an adequately sized airbox around the shock. Last year's YZ had a good box but it was small and most people had trouble trying to check the front edge of the filter for complete seal ing; there simply wasn't room for mosi hands. The `81 has a bigger airbox. The left side is expanded and the air inlet is raised to just under the seat. The wider left side makes filter seat checking easier and the seat surface on the airbox is smoother than last year's so the oiled foam filter contacts the airbox more fully. The filter's sealing edge is stiffer also, the cóm bination making filter seating an almost sure thing every time. The higher inlet helps keep water out of the filter in wet weather.
Plastic parts, fenders and side plates, are the same as before. They are well made and shaped right. The front number plate is made from thicker plastic than the Did and the arm that attaches it to the handlebar cross brace has a new buckle ;ystem. It's a nice number plate but it loesn't comply to 1981 AMA profession ;tandards because it's too small. It should measure 12 by 12 in. The gas tank looks the same but it’s actually a new part. It still holds 2.4 gal. of premix but it’s shaped differently. The rear part is slightly lower and narrower, the front slightly wider. The change makes sliding up on the tank easier.
YZ seats have been superior to many MX seats for some time; they are thick and shaped just right.
Starting is much improved by the new ignition. But the bike still demands a fast kick. Not necessarily a hard kick, but a fast one. And it’s best to have the kick lever at the top of the throw. Otherwise the engine won’t turn over fast enough and the familiar 465 pop is all that happens. It takes a while to get used too, then seems almost easy.
A slight vibration is felt while the engine is warming up but most of it disappears once the clutch is released. Acceleration is fantastic. The rear knobby spins all the way through each gear on hard surfaces. Loam or softer ground lets the rear tire hook up and the bike wheelies through each gear! Adding a tooth to the countershaft sprocket makes the power easier to use but it’s still awesome. The powerband is much improved from last year’s bike. The transition from low to mid-range is much smoother but a big power increase at the transition is still noticeable. The YZ465 simply has more power at lower rpm than any other bike. And it takes most people, even pro racers, a while to adapt. Grabbing a handful of throttle exiting a corner is completely wrong on a 465. The front wheel will lift and the rider exits over the berm. Keeping the bike one gear higher than your brain tells you to is the only way to ride the bike fast. The tremendous horsepower and torque at low revs works for the rider if ridden in what seems like a too-high gear. Even then, the bike demands a gentle roll-on of the throttle.
The H weighs 10 lb. more than the G. It topped the scales at 243 lb. with a half tank of gas. It’s not light but the weight isn’t noticed while riding because the abundant engine power can be used to move the bike around. The forks and rear axle contribute to the weight increase but 10 lb. seems like a lot.
Steering is precise. The 43mm forks direct the bike exactly where pointed. Exactly. Nothing flexes, moves around or causes a feeling of insecurity. Suspension compliance and overall action are almost perfect. The forks respond to small bumps, don’t bottom on large ones, and don’t need hours of dialing-in to do it. As delivered is the hot set-up for most riders. Of course accessory springs, both softer and stiffer, are available from Yamaha dealers but you’ll only need them if you’re very heavy or very light. We liked the fork oil level best at the stock level, 150mm from the top of the bottomed out stanchion tube. But of course, the level can be lowered to make the action softer or raised to make it stiffer at the bottom of the stroke.
The rear suspension worked best for most of our riders at the delivered settings. For motocross courses it’s right on like it is. For the desert we backed the spring preload off slightly and reduced the rebound damping by six turns, 20 clicks out from fully bottomed. Reducing the rebound damping for desert lets the rear wheel return quicker, as required for high speed desert terrain.
Riding the YZ465 is a super experience. It’s an eye opener regardless of the track or area it’s used. Acceleration is breath taking. Overshooting turns is normal for the first time 465 rider; not because of poor brakes, they’re some of the best, but because the bike gets from one place to the next quicker than you expect it to.
Balance is a high point with the 465. Out of sight wheelies are available to thei brave; any gear is okay, just turn on the throttle and lean back a little. The bike isn’t as wheelie prone as the G; that is, it doesn’t wheelie by itself as easily. The increase in weight shows up mostly at the front, helping overcome the tendency to automatically come up. The G’s weight* distribution was 46/54, the H’s works out to 47.7/52.3.
Cornering the H is a simple matter; just pick a line, any line, and go for it. The bike is neutral, liking berms, ruts or TT slides equally well. And changing your mind part way through is no problem with thq, YZ. If an inside line opens up the bike will gladly comply to the rider’s input and go where wanted.
We liked the 1980 YZ465 a bunch; we like the ’81 H even better. We couldn’t find anything wrong with the bike, except the front tire. It isn’t up to Metzeler standards, but is usable at any level but Pro." Otherwise the bike is great. It’ll cost you $150 more than it did last year, but still has to be considered a bargain.
YAMAHA YZ465H
$2149
Last year’s 465 had little competition. This year the other guys are shooting back. Maico has a 490, KTM a 495, Honda a 450, Kawasaki a 420 and Suzuki a 465. We haven’t tested all of them yet but intend to. Until we do, it’s hard to tell if the updated YZ will remain the best. If not, it won’t be far from it. Œ
